Bilateral Investment Treaties, or “BITs,” are both a response to and likely at least partly responsible for the significant increase in international investments in the last fifty years. BITs provide potential private investors government assurances regarding a variety of factors relevant to their investments. Among these assurances, BITs regularly address the tax authority that the host government has with regard to the foreign investor, often protecting that foreign private investor against changes to the host country’s tax system. If an investor believes the host country has violated the terms of the BIT, that investor can bring a claim against the country in front of an independent arbitration panel, whose decision will be final and binding. Because the power to tax is at the heart of what makes a sovereign authority a sovereign, restrictions on a sovereign’s ability to tax foreign investors, which can be enforced by an external body, threaten that sovereign’s very essence. As a result, tax provisions in BITs and the adjudication of those provisions by arbitration bodies must be carefully examined and potentially reconsidered, to protect the sovereign rights of governments to assess tax, to evolve their tax policies, and administer the laws of their countries in the best interests of their people.

This Article explains the background and use of BITs, explores theories of sovereignty, and then demonstrates that the current use of BITs to restrict governments’ ability to assess and collect tax within their borders threatens sovereign rights. The Article concludes by suggesting ways that the regulation of the taxation of international investments could be modified to protect sovereign rights.